Do Your Homework Before Ordering Mason Bees

With honeybee populations declining in recent years, gardeners have been searching for ways to encourage other pollinators to stop by and help out. One pollinator I hear mentioned more and more often is mason bees, and seed catalogs are increasingly offering all kinds of mason bee nesting boxes. They’re cute, these little bee condo things with all those little round holes. So I got to thinking I should buy one.

But then I stopped myself, wondering if it was okay to just introduce mason bees to my garden, my neighborhood, Minnesota? I emailed Jeff Hahn, a helpful entomologist with the University of Minnesota Extension Service, and he said he didn’t know a lot about mason bees. But he recommended I talk with Joel Gardner, a grad student who is studying them.

Joel didn’t have a lot to say, but what he did tell me made me think I need to do more research before ordering up some bees and a box. (Bees are sold separately.) Native bees, including mason bees, Joel says, are “always a good thing to invite into the garden.” Describing mason bees as “efficient” and “unobtrusive”, he told me that they don’t sting unless you really act like a whack job and grab and squeeze them. Don’t do that, and you can pretty much rest easy while gardening in their presence, even if you get close to their home.

What you do need to be concerned about is disease buildup, Joel says. Nests must be periodically cleaned or else fungus spores and mite populations can increase to the point where the nest can be harmful to the bees.

If you want to purchase mason bees, you need to be aware of the species you’re ordering since many bees are offered by out-of-state sources. Basically, the mason bee (Osmia lignaria) has two subspecies: Osmia lignarialignaria and Osmia lignaria propinqua. “Lignaria lives east of the Rockies and propinqua lives west, and introducing them outside their native range should be avoided,” Joel advises. Otherwise, you run the risk of spreading outside pests or diseases to local bee populations. And there could be other problems too.

After doing only a little bit more research on mason bees, I found that there is currently a lot of debate about the risks associated with the willy-nilly, nationwide shipment of these popular bees. From what I can tell, it’s just fine to get some. Just be sure to buy the right ones for your zip code. You’ll know you’re dealing with a reputable seller when they offer bees in this way.

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16 comments

Crown Bees is a good website to look at for more info. They’re not local to you, so won’t give the best Minnesota-based advice, but they won’t ship you non-native bees, and the website has lots of information and pictures of ways to prevent buildup of pests. I got my mason bees from there, and I can also vouch for their great customer service, which seems more service-oriented than sales-oriented.

Hi Michelle,
Thank you! I just took a look at Crown Bees and they have a lot of helpful information, as well as excerpts from writings about the problem of shipping non-native bees. I think I will get some mason bees this year once I read up on them a bit more. I appreciate your thoughts.

Good question. Mason bees are typically orchard pollinators. They need to be released when they’ll have a food source available, so it’s best to wait until some plants are in bloom, which is usually late April or early May in Minnesota. Raising mason bees successfully is not difficult, but there are some important things to understand. I would recommend reading the “What to Do” section of the Crown Bees website: http://www.crownbees.com/category/what-to-do/getting-started.

Hi Lynn,
I used to think that you had to order mason bees but I went to a talk by Marla Spivak, a bee researcher at the University of Minnesota, and she said that if you put up the bee house, they will find it. So I’d go that route. – m

The mason bees will find your nest box so there’s no need to buy bees. I think that the importation of bees from here to there increases the spread of viral diseases and pests. The honey bee pest, the varroa mite, got a strong foothold in the USA from because of transport bees being moved from crop to crop coast to coast.

Another super helpful thing with mason bees is to that a bit of your time to clean the actual coccoons. When buying or making a nest, get one that has paper tubes so these can be opened and the coccoons removed. The junk can be shifted out. Then (check U-Tube for great info & videos) the coccoons can be shifted with sand. The abrasion of the sand removes the nasty mites. Then the clean coccoons will be healthy and hatch with no mite infestation. I hope this info is helpful

Hi Barbara,
Thank you so much for your helpful note. I went to a talk on bees recently and learned that, as you say, if you put up a mason bee box, mason bees will come. So you don’t need to buy them. I really appreciate these cleaning tips, too. – Meleah

June 07, 2014

Rynn

Thanks for all the help! I am in Saint Paul and was just gifted with a mason bee hose and tubes. I am looking to install it ASAP. Will I need to insulate it in any way if we get more of our Polar Vortex routines as we did last year? If so what would you suggest?

I have read somewhere that you shouldn’t just drill holes
in say 2×4 lumber for you mason bee nest. the reason being that they will get dirty and infested with mites, but why couldn’t you discard the nesting blocks when they are vacant and put new ones in their place. This would certainly be the cheapest alternative for me.

I bought a mason house and put it up hoping the bees would find it. Instead I have black wasp /hornets nesting in it. :/. Not what I was hoping for….. Is there a way to discourage the wasps from using it? Does it mean I don’t have mason bees locally around?

We have a couple of points after reading through these comments. Meleah, thanks for writing this article. You bring out great topics. Not all companies think this through and just sells bees for money.

While Marla Spivac makes a valid point, she is missing a major component to mason bees. Mason bees need three things: pollen, holes, and good clayey mud. If you are missing one element, the bees won’t be there. Would you expect to find mason bees in a sandy environment? Neither would we. Not all mason bees use mud, just the early spring bees. some of the other 130 species will use leaf bits, resin, chewed up leaves, cotton from plants, etc. Not all bees use the same size hole… some are small bees wanting to use 1/8″ holes while others will nest in holes up to 5/16″.

Thus, “build it and they will come” isn’t always helpful. Beneficial wasps are gentle and will stuff their pests from your yard into the holes. that’s a good thing for pest removal!

If you want spring mason bees, you’ll need a supply of bees acclimated to your area and a source of clayey mud. We have it available for you if you feel your soil isn’t right. Do NOT underestimate this requirement.

Chemicals are also an issue… chem lawn or now called “true green” stinks to the bees and they’ll fly off. if your neighbor sprays, it will impact your bees as well. They will fly elsewhere.

Don’t buy bamboo shoots or drilled blocks of wood. If you can’t harvest your cocoons (open the holes) your bees will die off due to pests overrunning the holes.

If you’d like to learn more, see our website and do sign up for Bee-Mail, our monthly newsletter on how best to raise mason and leafcutter bees. It’s free and designed for your success.

Why do we care? We want to exchange your excess mason bees for free tubes/reeds. Inevitably, the bees of your backyard are used in nearby orchards for the farmer to gain more food. It’s a cool business plan and works.

This was really helpful. I got a bee house for mason bees mistakenly thinking some might just move in. So far there are none, so I am looking into buying native ones to the Seattle area. Will check out Crown Bees now. Thanks for the post!

We bought a nest box about eight years ago. And then another. And then some more. Never bought a bee, but now have probably 8-10 full neat boxes, and are working with a local researcher who is interested in them. So get a box, put it in a good location, and see what happens before you buy bees

Hi. My name is Meleah Maynard and I garden in crazy-ass cold, zone 4 Minneapolis, Minnesota. My first book, co-authored with Jeff Gillman, Decoding Gardening Advice: The Science Behind the 100 Most Common Recommendations, was recently published by Timber Press. Click here to email Meleah.